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rachis

[rey-kis] /ˈreɪ kɪs/
noun, plural rachises, rachides
[rak-i-deez, rey-ki-] /ˈræk ɪˌdiz, ˈreɪ kɪ-/ (Show IPA)
1.
Botany.
  1. the axis of an inflorescence when somewhat elongated, as in a raceme.
  2. (in a pinnately compound leaf or frond) the prolongation of the petiole along which the leaflets are disposed.
  3. any of various axial structures.
2.
Ornithology. the part of the shaft of a feather bearing the web.
3.
Anatomy, spinal column.
Also, rhachis.
Origin
1775-1785
1775-85; < Neo-Latin < Greek rháchis spine, ridge, backbone
Related forms
rachidian
[ruh-kid-ee-uh n] /rəˈkɪd i ən/ (Show IPA),
rachial
[rey-kee-uh l] /ˈreɪ ki əl/ (Show IPA),
rachidial, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for rachidial

rachis

/ˈreɪkɪs/
noun (pl) rachises, rhachises, rachides, rhachides (ˈrækɪˌdiːz; ˈreɪ-)
1.
(botany) the main axis or stem of an inflorescence or compound leaf
2.
(ornithol) the shaft of a feather, esp the part that carries the barbs
3.
another name for spinal column
Derived Forms
rachial, rhachial (ˈreɪkɪəl), rachidial, rhachidial (rəˈkɪdɪəl) adjective
Word Origin
C17: via New Latin from Greek rhakhis ridge
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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rachidial in Medicine

rachidial ra·chid·i·al (rā-kĭd'ē-əl, rə-) or ra·chid·i·an (-ē-ən)
adj.
Relating to the vertebral column; spinal.

rachis ra·chis (rā'kĭs)
n. pl. ra·chis·es or rach·i·des (rāk'ĭ-dēz', rā'kĭ-)
See spinal column.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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rachidial in Science
rachis
  (rā'kĭs)   
Plural rachises or rachides (rāk'ĭ-dēz', rā'kĭ-)
A main axis or shaft, such as the main stem of an inflorescence, the stalk of a pinnately compound leaf, the shaft of a feather, or the spinal column.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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